Mechanical stoker for forced-draft furnaces



Jan. 15 1924.

J. BRoNoLD MECHANICAL STOKER FOR FORCED DRAFT FURNAGES Filed March 281923 2 Sheets-Sheet l Jan. 15 1924. 1,480,988

J. BRONOLD MECHANICAL STOKER FOR FORCED DRAFT FUBNACES Filed March 281923 2 Sheets-Sheet 2 @J4 Mee Fatented dan. l5, i924.`

JOHANNES BRONOLD, 0F STEIERMUHLE, GERMANY, ASSIGNOR TO THE BABCOCKW'ILCOX COMPANY, OF NEW YORK, N. Y.

' MECHANICAL STOKER FOR FORCED-DRAFT FURNACES.

Application led March 28, 1923. Serial No. 628,364.

To all whom it may concern:

Be it known that I JOHANNES BRoNoLD, a citizen of Bavaria, Germany, andresiding at Steiermuhle, Saxony, Germany, have invented a certain newand useful Im provement in Mechanical Stokers for Forced-Draft Furnaces,of which the following is a specification.

The invention relates to mechanical stokers with forced draft furnaces,in which the draft is supplied only to the rear part of the grate whilethe front part of the grate is freely accessible, the sealing of the twoparts of the grate from one another being effected by means of a boxarranged between the upper and lower runs of the grate.

In accordance with the inwention, the front part of the grate is alsoenclosed, but is connected with suction means such as the suction inletof the fan or the chimney or an injector-like device operated by theforced draft arranged in such manner that a partial' vacuum is formed inthe front part of the grate.

Byvthis arrangement the following advantages are obtained. In the firstplace, if there is an excessive pressure in the combustion chamber,smoke or dust flowing out at the front of the grate is drawn off, sothat there is no inconvenience caused to the staff attending to theStoker. In the second place, owing to the partial vacuum at the iront ofthe grate the fire is drawn towards the front part of the grate, so thatgood combustion of the fuel is ensured and the fire cannot breakl up.Furthermore, the

y front part of the closure can be easily opened, Without, in any way,aecting the working of the forced draft so that the front part of thegrate is actually accessible.

The invention is illustrated in the accompanying drawing in which Fig. lis a section of part of a furnace showing one embodiment. Fig. 2 being asimilar view of a second embodiment 'adapted for use where the forceddraught is supplied to anumber of boilers from a common air supply pipe.

Fig. 3 is a View looking down on the up per run of the grate, everythingabove the upper run being removed and part of the grate gear being alsoremoved. In this view, parts are broken away and other parts beneath thegrate are shown dotted.

arrangement The furnace chamber l is bounded in front by a fuel'hopper 2and below by means of the upper run 3 of the mechanical grate. A box 4is arranged below the fuel inlet, between-the upper and lower runs,which box for practical purposes, seals off the front part of the gratefrom the rear part. elow this box is a sealing arrangement 5 which bearsagainst the lower run. The whole portion of the grate which isunderneath the furnace chamber is, therefore, cut 0H from the front partby means of the fuel lying on the front of the grate and by the twoseals 4 and 5. Below the rear part of the grate, forced draft isintroduced through a'duct 6.

The front part of the grate is closed in by means of a casing 7 providedwith a door 7 adapted to open outwardly. When the door is opened, accesscan be had to the front part of the grate, so that a fire slice can beused. The space thus closed 1n at the front part of the grate isconnected, in the embodiment shown in Figs. 1 and 3, to a duct 8 bymeans of openings 81 in the floor beneath the grate. Leading upwardly'from duct 8 is the inlet conduit` 82 of the fan 83. An opening 84 isarranged in the wall 85 to admit air to the conduit 82. The air thusentering the fan 83 is forced out and down and is admitted in duct 86through opening' 87, whence it flows into l duct 6 and beneath the rearortion of grate 3. In the duct 8 is arrange a pivoted damper operable bymeans of a spindle 10 with a crank 11. The arrangement is such that,when the damper 9 is closed the crank engages the door1 7', so that thelatter cannot be opened before the damper 9 is opened.

In the embodiment shown in Fi 2 the space enclosed in the front part oft e grate is connected by means of a duct 18 with a chamber 19 which istapered to form a nozzle leading to a duct 16, which leads to the rearpart of the grate.

Similarly to the embodiment previously described. a furnace chamber 1 isbounded in front by fuel hopper 2 and below by means of the upper run 3of the mechanical grate. A box 4 is arranged below the fuel inletbetween the upper and lower runs, to seal ofi' the front part of thegrate from the rear part. Below this box is a sealing 5 which bearsagainst the lower run. In this manner as in the'previously describedembodiment, the entire portion of the grate 3 beneath the furnacechamber 1 is effectively sealed from the front part by means of the fuellying upon the front part of the grate and by the two seals 4 and 5. Thefront part of the grate is closed in by. means of a casingl providedwith a door 72 by means of which access may be had to the front part ofthe grate when it is necessary to lbar the grate or for any otherpurpose.

The nozzle formed as above described is connected to distributing piping21, which serves to supply forced draft for several boilers. Thewall-forming plates 2O can be adjusted by; means of levers indicated indotted lines, to vary both the amount of the constriction in duct 16 andthe effective cross-sectional area of the duct 18, so that it ispossible4 to work under the most favourable conditions.

The modus operandi is as follows Forced draft is forced through the duct16 (from the distributinn piping 21 in the arrangement shown in `ig. 2)under the rear part of the grate. As soon as there is a pressure in thecombustion chamber 1, the flue gases forced into the front closed-inspace are drawn off. At the same time, however, owing to the partialvacuum in the closed-in space, a. suction action is exerted on the fuelin the front part of the combustion chamber so that the lire is drawn tothe front and cannot break up.

As the part of the stoker under pressure is sealed from the front partof the grate, the opening of the door 72 has no prejudicial effect onthe. working of the furnace.

1. In combination With a chain grate stoker, means for supplying forceddraft to the rear part of the grate, sealing means between said rearpart and the front part of the grate, an enclosure for said front part,said enclosure, together with the sealing means, defining in partachamber enclosingthe end of the grate, and means for maintaining Saidchamber under diminished pressure.

2. In combination with a chain grate Stoker, means for supplying forceddraft to the rear part lof the grate, sealing means between said rearpart and the front part of the grate, an enclosure for said front part,said enclosure, together with the' sealing means, defining in part achamber enclos* neeoeee ing the end of the grate, means for maintainingsaid chamber under diminished pressure and means for regulating saidsuction action.

3. ln ,combination with a chain grate stoker, means for supplying forceddraft to the rear part of the grate, sealing means between said rearpart and the front part of the grate, an enclosure for said front part,said enclosure, together with the sealing means, defining in part achamber enclosing the end of the grate, and means for maintaining saidchamber under diminished pressure, said means comprising an injectordevice operated by the forced draft.

Il. ln a. furnace, a mechanical grate, a duct having a constrictedportion for supplying forced draft to the rear o f said grate, sealingmeans between said rear part and the front part of the grate, anenclosure for said front part, such enclosed region having passagecommunicating with said duct at said constricted porJA whereby a suctionmay be created in said enclosure by the forced draft.

i5. ln a furnace, a mechanical grate, a duct having a constrictedportion for supplying forced draft to the rear of said grate, sealingmeans between said rear part and the front part of the grate, anenclosure for said front part, such enclosed region having .a passagecommunicating with said duct at said Constricted portion. whereby a.suction may be created in said enclosure by the forced draft and meansfor varying the amount of said constriction.

6. ln a furnace, amechanical grate, a duct having a constricted portionfor supplying forced draft to the rear of said grate. sealing meansbetween said rear part and the front part of the grate, an enclosure forsaid front part, such enclosed region having-a passage communicatingwith said duct at said constricted portion, whereby a suction may becreated in said enclosure by the forced draft, means for varying theamount of said constriction and independent mea-ns for regulating theeffective size of said passage.

ln testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.l

JOHANNES BRGNOLD. l-itnesses AoAri'roN SoMoN, nnnnrn Fincas.

